<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <!--5
      autocomplete="off"关闭自动补全
      readonly 将表单项设置为只读，数据会提交
      disabled 将表单项设置为禁用，数据不会提交
      autofocus 设置表单项自动获取焦点
    -->
    <input type="text" name="username" value="hello" readonly>
    <br/>
    <input type="text" name="username" autofocus>
    <br/>
    <input type="text" name="b">
</body>
</html>